The present invention relates to a fabrication technique for use in the manufacture of a semiconductor integrated circuit device, and, more particularly, to a technique which is applicable to resin molding in assembly using boards.
In conventional resin molding, opening degree adjustment means, which adjusts the opening degree of each air vent portion, is provided to the air vent portion of a mold, and a driving mechanism is provided to drive the opening degree adjustment means (for example, refer to Patent Document 1: Japanese Unexamined Patent Publication No. Hei 10 (1998)-92853 (FIG. 1)).
To perform transfer molding by mounting semiconductor integrated circuit chips on a multilayered printed wiring circuit board or the like and inserting the multilayered printed wiring circuit board or the like between molds, in contrast to general lead frames having a relatively small thickness error or the like, the thickness error is relatively large, and, hence, various drawbacks arise.
That is, when the thickness is excessively small, a gap is formed between an upper mold and a peripheral portion of the board, and, hence, the leaking of sealed resin occurs. Accordingly, to compensate for the small thickness, the clamping force is increased so as to depress the board by approximately 1% of the thickness, thus preventing the leaking of sealed resin. However, in this case, when the thickness is excessively large, excessive deformation arises in the board.
Further, it may be considered that the occurrence of voids or the like due to clogging of resin in the air vent portion can be suppressed by preliminarily preparing data corresponding to the thickness of a lead frame at the time of performing resin molding (resin filling) and adjusting the opening degree adjustment means in the air vent portion of a sealed mold by inputting such data at the time of resin sealing. However, in such a resin sealing operation, there arise drawbacks in that each time the thickness of the lead frame is changed, it is necessary to perform the operation of inputting data, and, at the same time, it is necessary to prepare input data for adjusting the opening degree adjustment means corresponding to the frame thickness.
Further, when the resin sealing operation is performed using a resin-made board which is softer than the lead frame, unevenness is liable to occur on a surface of the board due to warping of the board or the presence/non-presence of wiring, and, hence, in the above-mentioned resin sealing operation, there arises a drawback in that the opening degree adjustment of the air vent portion in response to a change in the thickness of the board and the shape of the surface of the board is extremely difficult.
Further, when it is necessary to perform resin molding of a plurality of boards using one mold at a time, the above-mentioned method requires a driving mechanism for the open degree adjustment means in the sealing mold for every air vent portion, and, hence, the structure of the sealing mold becomes complicated and large-sized.
Accordingly, it is an object of the present invention to provide a method of fabrication of a semiconductor integrated circuit device which can enhance the yield rate of products.
It is a further object of the present invention to provide a method of fabrication of a semiconductor integrated circuit device which can reduce the fabrication cost.
It is a still further object of the present invention to provide a method of fabrication method of a semiconductor integrated circuit device which can prevent the occurrence of drawbacks at the time of transporting boards in succeeding steps.
It is another object of the present invention to provide a method of fabrication of a semiconductor integrated circuit device which can reduce the mold clamping force.
The above-mentioned and other objects and novel features of the present invention will become apparent from the description of this specification and the attached drawings.